1. Field of the Invention
The present invention relates to a jet propulsion device for watercraft and aircraft, as well as to circulating pumps. The fluid, flowing into a jet propulsion pipe, is accelerated by a rotor, formed as a screw, in a direction opposite to the intended thrust direction. The outer edge of the screw is fixedly connected to the inner jacket of the jet propulsion pipe, such that the screw and the jet propulsion pipe are rotating jointly. The jet propulsion pipe is driven at its outer jacket and is supported in an enveloping pipe or in an enveloping pipe casing or the like.
2. Brief Description of the Background of the Invention Including Prior Art
Such a jet propulsion device is known from the German Utility Patent 1,997,210. A propulsion element, developed as a rotor and disposed in the interior of the jet propulsion pipe, is formed of a single-piece full, solid screw, covering the clear inner space of the jet propulsion pipe. This full, solid screw protrudes at the two front faces of the jet propulsion pipe and projects in propulsion direction into a fixed-position input port and, on the other side, also into a fixed-position discharge port, furnished with paddles and exhibiting an opposite course direction. The jet propulsion pipe is driven by a gear ring, disposed in its center. Since in case of such a screw, there is generated in the neighborhood of the axis an outwardly directed force and on the outer side an inwardly directed force based on the rotation action on the water flowing through, the complete water volume is put into a spinning motion, which causes vortex losses on the discharge side. A following stream deflector can compensate these losses only in part over a limited range of rotation speed. The paddles protruding into the inlet port generate a strong vortex formation. The hydraulic flow-passage cross-section is in addition narrowed based on the strong vortex formation such that only a part volume of the advancing fluid medium is captured and that the power yield thus resulting from the product "mass" times "acceleration" is correspondingly low.
A propeller is known from the German Patent DE-PS 860,154, where the wings or paddles are penetrated and interrupted by a carrying-wing-like nozzle ring. In the latter case, the inner wing parts are to assume a different pitch. It is to be achieved based on the carrying-wing-like structure of the nozzle ring that a strongly converging water stream flowing to the propeller generates an underpressure on the inner face of the propeller and an overpressure on the outer face of the propeller, in the sense of an additional thrust generation. As taught in the two embodiments, of course, the nozzle has to have approximately the length of the projection of the wing width.
A jet pipe is already disclosed in the German Patent Application Laid Open DE-OS 3,343,605 relative to one embodiment of the invention. The intake is structured convergingly and is narrowed by a displacement body to an annular space.
In view of a further embodiment of the invention, the German Patent Application Laid Open DE-OS 3,718,954 teaches already a propeller structure where the outer ring of a propeller is formed as a rotor. A stator surrounding the outer ring of the propeller and cooperating with the propeller is coordinated to the rotor in the casing.
Further, the book in the German language by Richard Geissler, "Der Schraubenpropeller" (The Screw Propeller"), Dissertation, Julius Spring, Berlin, 1918, page 18, mentions a screw propeller. In this case, the wings of the screw propeller are comprised of bands. The bands, exhibiting a half-step winding and wound in themselves, are supported opposite to each other with their ends by way of webs of a drive axis attached in a plane at hubs of a drive shaft. The bands are supported with their center part at a further hub. The fluid, flowing in this case in a direction parallel to the drive axis, is whirled and swirled in an energy-consuming way by the spinning webs such that the power yield becomes very small.